/*  
 *  Copyright 2006 Paul Jack.
 *
 *  This file is part of the Dex compiler suite. 
 *  
 *  Dex is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by the
 *  Free Software Foundation; either version 2 of the License, or (at your
 *  option) any later version.
 *  
 *  Dex is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
 *  Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */
package dex.misc;


import java.util.Set;


/**
 * A cache.  The set only ever retains the original elements added.
 *
 * @param <T>  the type of the cache
 */
public interface Cache<T> extends Set<T> {

	
	/*
	 * Caches the given element.  This behaves exactly like
	 * {@link Set#add(Object)}, except that the if the object
	 * already exists in this set, then that object is returned.
	 * 
	 * @param element the element to add to the set
	 * @return  the given element, or an equal previously added
	 *    element if such an element exists
	 */
	<K extends T> K cache(K element);
	
}
